System and apparatus for reducing liquid water emissions in the exhaust of a hydrogen engine

ABSTRACT

A system for reducing the volume of liquid water emitted from an exhaust pipe of a hydrogen-fueled engine is described. A vaporizer unit has a main body portion, a spraying assembly and a vapor port. The main body portion surrounds at least a portion of an exhaust manifold of the engine. The vapor port couples the vaporizer unit to the exhaust pipe of the engine via a vapor pipe. The spraying assembly is configured to spray liquid water over at least a portion of the exhaust manifold. The apparatus also includes a liquid-vapor separator placed inline in the exhaust pipe of the engine, and a sump coupled to the exhaust pipe. The sump collects liquid water recovered by the liquid-vapor separator. Finally, the apparatus includes a pump coupled to the sump and to the spraying assembly and configured to provide the collected liquid water to the vaporizer unit.

BACKGROUND

This following disclosure relates to improvements in the field ofengines. In particular, this disclosure relates to an improved systemand apparatus for reducing liquid water emissions from a hydrogenengine.

In recent years, there has been a keen interest in finding andexploiting alternative energy sources, particularly for vehicles such asbusses, cars, trains and heavy equipment that are used by publicentities. Such pursuits have resulted in a number of advances in vehicleengine design being brought to market over the last few years, includingfor example, the direct-injection diesel engine. One advance in enginedesign is the introduction of hydrogen-fueled engines. A hydrogen-fueledengine uses elemental hydrogen of easily obtained industrial purity as afuel in an internal combustion engine. One example of a hydrogen engineis a hydrogen-conversion engine modification, which converts an enginedesigned to burn petroleum-based fuels to allow the engine to usehydrogen as a fuel.

Hydrogen fueled engines are of particular interest due to theirinherently clean and low exhaust emissions. In particular, a hydrogenengine produces water, water vapor, and, in some instances, very smallproportions of nitrogen oxides as by-products. Furthermore, a hydrogenengine produces essentially no carbon-based by-products at all, such ascarbon monoxide and carbon dioxide. Therefore many hydrogen enginesqualify as “zero emission” under certain governmental standards.

However, one problem with the emissions of a hydrogen engine is theoccurrence of liquid water in the exhaust pipe of a vehicle. Water vaporemitted from a hydrogen engine, particularly in a hydrogen-conversion,can easily condense in the exhaust line of the engine and cause a numberof problems. In particular, if excess fluid water is allowed to accretein an exhaust line, it may rust internal surfaces and components. It isalso undesirable to have liquid water emitted directly from a tailpipeas an effluent, as many vehicles, and also the attendant streetinfrastructure for the vehicles, are not designed to accommodate asteady flow of such effluent. Further, the cumulative effect ofdepositing significant amounts of liquid water on a roadway may resultin an unsafe roadway conditions, such as reduced driver visibility dueto water spraying off of vehicle tires, reduced roadway contact due towet pavement, or if the water were to freeze. These adverse roadwayconditions can worsen in heavily populated areas and create orcontribute to multi-vehicle accidents. It is therefore desirable toprovide advancements to the art that overcome these and otherdisadvantages.

SUMMARY

According to an embodiment described herein, an apparatus for reducingthe volume of liquid water emitted from an exhaust pipe of ahydrogen-fueled engine is provided. The apparatus includes a vaporizerunit comprising a main body portion, a spraying assembly and a vaporport portion. The main body portion (or “housing”) surrounds at least aportion of an exhaust manifold of the engine. Furthermore, the main bodyportion is defined by an inner surface and an outer surface. The innersurface is defined in part by at least a portion of the exhaust manifoldand the vapor port portion is defined by an opening in the vaporizerunit that is coupled to the exhaust pipe via a vapor pipe. As describedherein, the spraying assembly comprises at least one spray nozzlesupported by the main body portion and configured to spray liquid waterover at least a portion of the exhaust manifold. The apparatus alsoincludes a liquid-vapor separator placed inline in the exhaust pipe ofthe engine, and a sump coupled to the exhaust pipe. As described herein,the sump is configured to collect liquid water recovered by theliquid-vapor separator. Finally, the apparatus includes a pump coupledto the sump and to the spraying assembly and configured to provide thecollected liquid water to the vaporizer unit. In one embodiment, theapparatus can further include insulation, such as sprayed-on insulation,on the outside of the entire apparatus to further reduce heat loss andlessen the amount of liquid water resulting from the cooling of theexhaust vapor.

According to another embodiment, a system for reducing the volume ofliquid water emitted from the tailpipe of a hydrogen fueled engineincludes means for collecting liquid water that condenses in thetailpipe from exhaust gasses emitted by the engine. The system alsoincludes means for vaporizing the liquid water using waste heat from theengine. Finally, the system includes means for returning the vaporizedcollected water to the atmosphere via the tailpipe.

According to still another embodiment, a method for reducing the volumeof liquid water ultimately emitted from an exhaust pipe of a hydrogenfueled engine is described. The method includes collecting liquid waterfrom the exhaust pipe, vaporizing the water using waste heat from theengine, and then emitting the vaporized water to the atmosphere via theexhaust pipe.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view depicting an apparatus for reducing thevolume of liquid water emitted from an exhaust pipe of a hydrogen-fueledengine in accordance with one embodiment.

FIG. 2 is cross-sectional view of the apparatus of FIG. 1 as taken along2-2 of FIG. 1.

FIG. 3 is another cross-sectional view of the apparatus of FIG. 1, astaken along 3-3 of FIG. 1.

FIG. 4 is another cross-sectional view of the apparatus of FIG. 1, astaken along 4-4 of FIG. 1.

FIG. 5 is fragmented sectional view of the apparatus of FIG. 4 as takenalong 5-5 of FIG. 4.

FIG. 6 is a flow diagram illustrating a method, according to anotherembodiment.

FIG. 7 is a side elevation view depicting an apparatus for reducing thevolume of liquid water emitted from an exhaust pipe of a hydrogen-fueledengine in accordance with a further embodiment.

FIG. 8 is a side elevation view depicting an apparatus for reducing thevolume of liquid water emitted from an exhaust pipe of a hydrogen-fueledengine in accordance with yet another embodiment.

DETAILED DESCRIPTION

FIG. 1 is a plan view depicting an example of a system and apparatus forreducing the volume of liquid water emitted from an exhaust pipe of ahydrogen-fueled engine, in accordance with one embodiment. FIG. 1depicts a liquid water reducing system 100 that will be discussed indetail in the following description of FIGS. 1-5. Generally, waterreducing system 100 includes components that provide means forcollecting liquid water that condenses in the tailpipe from exhaustgasses emitted by the engine, components that provide means forvaporizing the liquid water using waste heat from the engine, andcomponents that provide means for returning the vaporized collectedwater to the atmosphere via the tailpipe. Various components of liquidwater reducing system 100 are depicted in the Figures and the followingdescription with reference to a hydrogen fueled engine. The operation ofsuch engines is well known in the art, and is not the subject of thisdiscussion, and therefore will not be further discussed. Further, itwill be appreciated that the system described herein can be used withother engines wherein liquid effluent is undesirable.

Turning now to FIG. 1, the water reducing system 100 is depictedincluding a vaporizer unit 170 that provides means for vaporizing liquidwater using waste heat from the engine and which comprises a main bodyportion 110, a spraying assembly 111 and a vapor port 112. In oneembodiment, the main body portion 110 of the vaporizer unit 170 isfurther defined by a front face 175, and four side faces 171, 172, 173,174 respectively. As shown in FIG. 1, the main body portion 110surrounds at least a portion of an exhaust manifold 113 of the engine201, depicted in FIG. 3. Means for returning the vaporized collectedwater to the atmosphere via the tailpipe are also provided. For example,FIG. 1 depicts the main body portion 110 of the vaporizer unit 170coupled to an exhaust pipe 130 via a vapor port 112.

Means for collecting liquid water that condenses in the tailpipe fromexhaust gasses emitted by the engine are also depicted in FIG. 1. Oneexample of liquid collection means includes a liquid-vapor separator150, as is shown placed inline with the engines exhaust pipe 130.Another example of liquid collection means includes a sump (or “liquidcollector”) 155 configured to collect liquid water recovered by theliquid-vapor separator 150, and is depicted in FIG. 1 as being coupledto the liquid-vapor separator 150 and to the exhaust pipe 130. Yetanother example of liquid collection means can include a pump 160configured to provide the collected liquid water to the vaporizer unit170. In FIG. 1 the pump 160 is shown coupled to the sump 155 via a drain156. Pump 160 can be any pump suitable for moving water from the sump155 to the spraying assembly 111, such as for example a vibratory pumpor a rotary vane pump, as will be known to the skilled practitioner. Inone embodiment (not shown), the liquid water reducing system 100includes a feedback control system for monitoring the temperature of themanifold 113 and the water level in the sump 155 and for controlling thepump and spraying assembly so that the liquid water reducing system 100is operational only when predetermined operational conditions aredetected, such as for example, a baseline manifold 113 temperature andadequate water level for safe pump 160 operation.

Other means for vaporizing liquid water using waste heat from the engineare depicted in FIG. 1. For example, one component of vaporizing meanscan include a liquid return line 120, as is shown in FIG. 1, thatcouples the pump 160 to the spray assembly 111 of the vaporizer unit170. Generally, the spray assembly 111 can include any components forspraying liquid, such as for example spray nozzles, spray nozzlemounting hardware, and any other components that allow the spraying ofliquid water or other liquids. In one embodiment, the liquid return line120 is at least partially disposed proximate to a section of the exhaustpipe 130 that is between the pump 160 and the exhaust manifold 113. Inone embodiment the liquid return line 120 is covered with aheat-retaining insulation 121 to allow recovered liquid to be pre-heatedprior to providing the recovered liquid to the vaporizer unit 170. Inanother embodiment, the heat-retaining insulation material 121 comprisesone or more materials such as, but not limited to, graphite composite,fiberglass, aluminized polyester, aluminum, ceramic, and the like. Inyet another embodiment, all or a portion of the exhaust pipe 130 can becovered with a heat-retaining insulation 231 to increase the transfer ofheat to the liquid return line 120 and reduce condensation in theexhaust pipe.

In one embodiment, the liquid-vapor separator 150 includes a housing 153that defines an enclosed space 154 interior to the separator 150 thatcan house a catalyst or other medium 151 to facilitate a separation ofliquid from vapor. In another embodiment, the medium 151 in theliquid-vapor separator is a material having a large surface area thatenhances the condensation surface area of the interior space 154 ofliquid-vapor separator 150, without unduly restricting the flow ofvapor. Surface area enhancing materials used for the medium 151 caninclude, but are not limited to, plastic beads, glass beads, ceramicbeads, metal wool, fiberglass wool, and expanded metal.

Other means for collecting liquid water that condenses in the tailpipefrom exhaust gasses emitted by the engine are also depicted in FIG. 1.As shown in FIG. 1, the liquid water reducing system 100 also includeswater collection means such as a drain channel 135 disposed between theliquid-vapor separator 150 and an ambient exhaust point 131 of theexhaust pipe 130. In one embodiment, the drain channel 135 is slopedtowards, and drained into, the sump 155. One embodiment furthercomprises a fluid deflector 157 that affixes to the exhaust pipe 130 andis directed into the sump 155, such that water collected in the sump 155is prevented from re-entering the exhaust pipe 130 from the sump 155 asexhaust gasses pass through the liquid-vapor separator 150. In stillanother embodiment, a filter screen 132 is positioned above the drainchannel 135 to allow fluid to drain from the exhaust pipe 130 to thedrain channel. The filter screen 132 can also assist in preventingliquid from re-entering the exhaust pipe 130. In order to furtherillustrate the features of the liquid water reducing system 100 shown inFIG. 1, alternative views of the various embodiments shown in FIG. 1will now be discussed in FIGS. 2-5.

FIG. 2 is cross-sectional view of the apparatus of FIG. 1 as taken along2-2 of FIG. 1. As discussed in the description of FIG. 1 above, theliquid water reducing system 100 includes a vaporizer unit 170. In theexample depicted in FIG. 2, the front face 175 of the main body portion110 is substantially rectangular and defined by one or more openings 221for one or more output pipes 230 of the exhaust manifold 113. The fourside faces of the main body portion 110 (shown in FIG. 1 as 171, 172,173, 174) extend generally perpendicularly from an edge of each of thefour sides of the front face 175 to form an open bottomed box having aninterior space 220.

In the example depicted in FIG. 3, the main body portion 110 ispositioned on the exhaust manifold 113 such that each of the side faces(e.g., 171, 172, 173, 174 of FIG. 1) enclose at least a portion of theexhaust manifold, and the one or more output pipes 230 traverse theinterior space 220 of the main body portion 110 and exit the one or moreopenings 221 at the front face 175 of the main body portion 110.Further, in the example depicted in FIGS. 1 and 3, the vaporizer unit170 is affixed to the housing 110 by mechanical coupling, such a weld, abolt, a rivet, etc. The main body portion 110 can be manufactured from amaterial such as, for example, plastic, graphite composite, aluminum,steel or ceramic. Further, output pipes 230 can be sealed at theopenings 221 in the housing (main body portion 110) using a sealant suchas silicone or the like. In the example depicted in FIG. 2, the vaporport 112 joins the main body portion 110 of the vaporizer unit 170 tothe exhaust pipe 130 at a point below an expansion section 240 of theexhaust manifold 113. In other embodiments however, the vapor port 112can be joined to the exhaust manifold 113 or the exhaust pipe in anysuitable location. The liquid return line 120 is also shown in FIG. 2affixed to the exhaust pipe 130 along a lower portion of the exhaustpipe. It should be appreciated, however, that the liquid return line 120can be positioned in any suitable manner along the length of the exhaustpipe 130, and is not limited to the embodiment illustrated in FIG. 2. Asshown in FIG. 2, a heat retaining insulation material 231 can surround aportion of the exhaust pipe 130. In this example, the heat retaininginsulation 231 can increase the transfer of heat from the exhaust pipe130 to the liquid return line 120.

FIG. 3 is another cross-sectional view apparatus of FIGS. 1 and 2 astaken along 3-3 of FIG. 1. As shown in FIG. 3, the main body portion 110includes an inner surface 315 and an outer surface 316. In the exampleshown, the inner surface 315 is defined in part by at least a portion ofthe exhaust manifold 113. Further, in the example shown, the vapor portportion 112 (“vapor pipe”) is defined by an opening 313 in the vaporizerunit 170 that couples the vapor port 112 to the exhaust pipe 130.

As further illustrated in FIG. 3, the spraying assembly (111 of FIG. 1)comprises one or more spray nozzles (111 a and 111 b) that are supportedby the main body portion 110 and configured to spray liquid water intothe interior volume 220 of the main body portion 110, and in particularover at least a portion of the exhaust manifold 113 (and moreparticularly, over at least a portion of the output pipes 230).Generally, the spray nozzles (e.g., 111 a and 111 b) can includethreaded mounting hardware and seals and the like that allow them to bemechanically coupled to the main body portion 110 with a water-tightseal. As depicted in the example shown in FIG. 3, the spray nozzles 111a and 111 b are coupled to corresponding liquid return lines 120 a and120 b, respectively, that are fed by a main liquid return line (e.g.,120 of FIGS. 1 and 2). While FIGS. 1 and 3 depict the spray nozzles 111a, 111 b as being positioned at only the right side 172 of the housing110, it will be appreciated that the spray nozzles can be positioned inother locations as well. For example, spray nozzles can be positioned atany or all (or any combination thereof) of the sides 171-175 of thehousing 110 (and including the back side of the housing 110 opposite thefront face 175).

The spray nozzles 111 a, 111 b are configured to generally atomizeliquid (water, typically) from the liquid return line 120 and dispersethe liquid over the output pipes 230. However, in one variation ratherthan atomizing the liquid, the liquid can be dripped directly onto theoutput pipes 230. In general, various spray nozzles and the techniquesfor implementing them will be known to the skilled practitioner andtherefore will not be further discussed.

In one variation, the inner surface 315 of the main body portion 110 canbe coated with a sealant (not shown) that provides a water-tight sealover the entire inner surface 315 of the main body portion. The sealantcan be a high-temperature silicone, for example.

As illustrated in FIG. 3, the exhaust manifold 113 can comprises aplurality of separate outlet pipes 230 and a header (e.g., 240 of FIG.2) that couples the plurality of outlet pipes 230 to the exhaust pipe130. In another embodiment (not shown) a valve assembly placed in theopening 313 of the vapor port 112 can be configured to reduce the amountof back-flow exhaust gasses from the exhaust pipe 130 that can enter themain body portion 110 through the vapor port 112.

In still another variation, the main body portion 110 can include aflange 314 for mechanically coupling the main body portion 110 to theengine 201. In one embodiment, the flange 314 includes a plurality ofthrough-holes for mechanical couplers, such as rivets, bolts, etc., forcoupling the housing to the engine 201. Further, sealing agents, such assilicone and the like, can be used to seal the main body portion 110 tothe engine 201. FIG. 3 also depicts a heat retaining insulation material231 that can surround all, or a portion of, the exhaust pipe 130, aswell as all, or a portion of, the output pipes 230 exterior of thehousing 110. Although not depicted in FIG. 1, the insulation material231 can also surround all, or a portion of, the liquid-vapor separator150. In the illustrated example, the heat retaining insulation 231 canincrease the transfer of heat from the exhaust pipe 130 to the liquidreturn line 120, and further retain existing heat from the output pipes230.

In the example depicted in FIGS. 1-3, the main body portion (“housing”)110 of the system 100 is depicted as being generally in the shape of arectangular box, with the output pipes 230 exiting the housing 110 atthe front face 175. However, it will be appreciated that the housing 110can be formed in other shapes in cross section (top section, sidesection, and/or end section), such as elliptical, spherical, and otherpolygonal shapes. Further, it will be appreciated that the output pipes230 can exit the housing 110 at openings 221 at locations other than thefront face 175. For example, the output pipes 230 can exit the housing110 at the bottom side 173, the left side 174, the right side 172, thetop side 171, the back side (not numbered, but opposite to the frontface 175), or combinations thereof. Moreover, while FIGS. 1-3 depict theoutput pipes 230 as each exiting the housing 110 at distinct openings221, in another example the header 240 that joins the output pipes 230together into the exhaust pipe 130 can also be enclosed within thehousing 110, thus reducing the number of openings 221 within the housing110. Additionally, while openings 221 can be sealed against output pipes230, in another example there can be a gap between the openings and theoutput pipes 230. In fact, rather than exhaust vapor from the interior220 of the housing 110 back into the exhaust pipe 130 via vapor port112, in another embodiment some (or all) of the vapor within theinterior 220 of the housing 110 can be exhausted directly to the ambientatmosphere through outlet 313.

In one variation depicted in FIG. 8, rather than the exhaust vapor (fromwithin the housing 110) being reintroduced into the exhaust pipe 130 viavapor port 112, the vapor port 193 can attach to a separate pipe whichdirects the vapor exiting the body portion 110 directly to theliquid-vapor separator 150. This separate pipe can encase the exhaustpipe 130 as depicted, can be placed adjacent the exhaust pipe (notshown), or can be routed within the exhaust pipe (also not shown).Further, as indicated above, vapor exiting the body portion 110 can berouted directly to the ambient atmosphere as indicated in FIG. 7 byseparate pipe 191. Techniques for implementing these variations will bereadily apparent to the skilled practitioner in light of the presentdisclosure, and therefore further elaboration is not required.

In general, the housing 110 comprises a jacket that encloses at least aportion of the output pipes 230. The spray assembly 110 sprays liquid(typically liquid water) into the interior 220 of the housing 110 andonto the portion of the output pipes 230 enclosed by the housing 110.Heat from the output pipes 230 causes at least a portion of the liquidwater sprayed into the interior 220 of the housing 110 to vaporizewithin the interior of the housing, and the vapor within the interior ofthe housing is then exhausted back into the exhaust pipe 130 or toanother location (such as to the ambient atmosphere).

FIG. 4 is another cross-sectional view of the apparatus of FIG. 1, astaken along 4-4 of FIG. 1, illustrating additional features than can beprovided. As depicted in FIG. 4, the exhaust pipe can 130 include adrain channel 135 that is mechanically coupled to the exhaust pipe 130.The drain channel 135 can be composed of a material such as, but notlimited to, stainless steel, aluminum alloy, plastic, resin, andgraphite composite. As shown in the example depicted in FIG. 4, thedrain channel 135 is coupled to the exhaust pipe 130 with connectors(421 a and 421 b) such as screws, rivets, bolts, etc. The drain channel135 can also be affixed to the exhaust pipe 130 with a weld, an epoxy oranother mechanical coupling technique, or it can be part of an integralextrusion that includes the exhaust pipe 130 and the drain channel 135.A screen 132 can be provided between the exhaust pipe 130 and the drainchannel 135. The screen can be selected from any conventional heattolerant screen material that allows water to pass through to the drainchannel 135, such as metal screen, carbon composite screen andhigh-temperature plastic screen, for example.

FIG. 5 is fragmented sectional view of the apparatus of FIG. 4, as takenalong 5-5 of FIG. 4. As shown in FIG. 5, the screen 132 separates theexhaust pipe 130 from the drain channel 135. Fasteners 421 a and 421 bare also illustrated in FIG. 5, in one exemplary configuration forattaching the drain channel 135 and screen 132 to the exhaust pipe 130.

Now that several exemplary embodiments of the components of the liquidwater reducing system have been illustrated, an application of thecomponents to reduce the occurrence of liquid water in the exhaust lineof a hydrogen-powered engine will be discussed.

FIG. 6 is a flow diagram illustrating a method, according to anembodiment. FIG. 6 illustrates a method 600 for method for reducing thevolume of liquid water ultimately emitted from an exhaust pipe of ahydrogen fueled engine. In one embodiment, method 600 is implementedwith components of the exemplary system and apparatus according to oneor more of the embodiments described with reference to FIGS. 1-5. Method600 begins in step 610. Various steps of the method 600 are describedwith respect to a method 600 for reducing the volume of liquidultimately emitted from an exhaust pipe of an engine. In someimplementations, certain steps of method 600 can be combined, performedsimultaneously or in a different order, without deviating from theobjective of method 600 or without producing different results.

In step 610, liquid (typically, but not limited to, water) is collectedfrom the exhaust pipe of an engine (which can be, for example, ahydrogen fueled engine). The liquid (water, in the present example) iscollected at any time that liquid is accumulating in the exhaust pipe ofthe engine. In general, the liquid water is collected by the force ofgravity as the water flows from various part of the liquid waterreducing system 100 into a sump (e.g., item 155, FIG. 1). In oneembodiment, the water is collected as water condensing in the exhaustpipe 130 (FIG. 1) is directed to the sump (155) via a liquid deflector157. In another embodiment, water is collected in the sump (155) via awater-vapor separator 150 that separates liquid water from vapor, andcan also cause water vapor close to the liquid state to condense intoliquid. In one embodiment, the collected liquid water can be also bedrained from the sump 155 to a pump 160 (either directly, or via a drainline 156).

In step 620 (FIG. 6), the collected liquid water is vaporized usingwaste heat from the engine 201 (FIG. 1). The collected liquid water isprovided at any time that the liquid reducing system (e.g., system 100,FIG. 1), and in particular the pump (e.g., 160, FIG. 1) and thevaporizer unit (e.g., 170, FIG. 1) are operational. In one embodiment, afeedback control system can control the operation of the vaporizing sothat the liquid water reducing system (e.g., 100, FIG. 1) only becomesoperational when the engine manifold (e.g., 113, FIG. 1) is heated to apredetermined temperature and/or there is a safe level of water in thesump 155 with which to operate pump 160. In another embodiment, the stepof vaporizing further includes the steps of providing the collectedwater from the pump 160 to the vaporizer unit 170 via a liquid returnline (e.g., line 120, FIG. 1) and then spraying the collected liquidover the exhaust manifold (e.g., 113, FIG. 1). In another embodiment,the collected water is provided to the vaporizer unit 170intermittently, based on a predetermined amount of collected water inthe sump 155.

In one embodiment, the vaporizer unit 170 includes at least one spraynozzle disposed within a jacket (e.g., main body portion 110, FIG. 1)that is formed at least partially around an exhaust manifold (113,FIG. 1) of the engine. In another embodiment, the collected water ispre-heated prior to spraying by thermally coupling a liquid return line(e.g., 120, FIG. 1) to at least a portion of the exhaust pipe 130 of theengine. In another embodiment, the collected water is sprayed over themanifold with the spray nozzles and the sprayed pre-heated watercontained within the water-tight jacket is vaporized by the heat of theexhaust manifold. In yet another embodiment, the collected water isfiltered and/or strained prior to the pumping it to the vaporizer unit170 to prevent clogs in the spray nozzles, and to preserve pump life.

In step 630 (FIG. 6), the vaporized water is emitted to the atmospherevia the exhaust pipe (e.g., via tailpipe 131, FIG. 1). The vaporizedwater is emitted at any time that the vaporized water is produced, as instep 620. In one embodiment, the vaporized water is emitted to theatmosphere via the exhaust pipe 130 by directing the vaporized water toa vapor port 112 that is in fluid communication with the exhaust pipe130. In another embodiment, the exhaust pipe 130 is insulated with aheat-retaining insulation to reduce the amount of water vapor thatre-condenses in the exhaust pipe. In yet another embodiment, a valveassembly placed between the exhaust pipe 130 and the vapor port 112reduces exhaust gas back-flow from the exhaust pipe 130 into the mainbody portion 110 of the vaporizer unit 170. In another embodiment,exhaust gasses from the exhaust pipe 130 are directed into the main bodyportion 110 with a valve assembly to increase the vaporization rate ofsprayed recovered water prior to emission into the exhaust port 112.

A further embodiment provides for an apparatus including a jacket (e.g.,jacket or housing 110, FIGS. 1-3) configured to cover at least a portionof an exhaust manifold (e.g., item 113, FIGS. 1-3) of an engine (e.g.,item 201, FIG. 3). The apparatus of this embodiment further includes aliquid collector (e.g., sump 155 of FIG. 1) configured to collectliquids within an exhaust pipe (e.g., item 130 of FIGS. 1-5) connectedto the exhaust manifold, and a pump (e.g., item 160, FIG. 1) configuredto pump liquids from the liquid collector to the jacket. The apparatusalso includes a spray assembly (e.g., 111, FIG. 1) configured to sprayliquids from the pump over the portion of the exhaust manifold coveredby the jacket.

Yet an additional embodiment provides for an apparatus including anengine (e.g., item 201, FIG. 3), an exhaust manifold (e.g., item 113,FIGS. 1-3) in fluid communication with the engine, and an exhaust pipe(e.g., item 130, FIGS. 1-3) in fluid communication with the manifold.The apparatus further includes a jacket (e.g., jacket or housing 110,FIGS. 1-3) configured to cover at least a portion of the exhaustmanifold (e.g., item 113, FIGS. 1-3) of then engine (e.g., item 201,FIG. 3). The apparatus of this embodiment further includes a liquidcollector (e.g., sump 155 of FIG. 1) configured to collect liquidswithin an exhaust pipe (e.g., item 130 of FIGS. 1-5) connected to theexhaust manifold, and a pump (e.g., item 160, FIG. 1) configured to pumpliquids from the liquid collector to the jacket. The apparatus alsoincludes a spray assembly (e.g., 111, FIG. 1) configured to sprayliquids from the pump over the portion of the exhaust manifold coveredby the jacket.

A further embodiment provides for a vehicle having an engine (e.g., item201, FIG. 3), an exhaust manifold (e.g., item 113, FIGS. 1-3) in fluidcommunication with the engine, and an exhaust pipe (e.g., item 130,FIGS. 1-3) in fluid communication with the manifold. The apparatusfurther includes a jacket (e.g., jacket or housing 110, FIGS. 1-3)configured to cover at least a portion of the exhaust manifold (e.g.,item 113, FIGS. 1-3) of then engine (e.g., item 201, FIG. 3). Theapparatus of this embodiment further includes a liquid collector (e.g.,sump 155 of FIG. 1) configured to collect liquids within an exhaust pipe(e.g., item 130 of FIGS. 1-5) connected to the exhaust manifold, and apump (e.g., item 160, FIG. 1) configured to pump liquids from the liquidcollector to the jacket. The apparatus also includes a spray assembly(e.g., 111, FIG. 1) configured to spray liquids from the pump over theportion of the exhaust manifold covered by the jacket.

It is understood that the methods and apparatus disclosed herein can beembodied in other specific forms not described that do not depart fromits spirit or essential characteristics. The described embodiments areto be considered in all respects only as illustrative and notrestrictive, the scope of the embodiments being defined by the appendedclaims and equivalents thereof.

1. A method to reduce the volume of liquid water ultimately emitted froman exhaust pipe of a hydrogen fueled engine comprising: collectingliquid water from the exhaust pipe; vaporizing the liquid water usingwaste heat from the engine; and emitting the vaporized liquid water tothe atmosphere.
 2. The method of claim 1 further comprising pumping thecollected liquid water to a vaporizer unit wherein the vaporizing isperformed.
 3. The method of claim 1 wherein the vaporized liquid wateris emitted to the atmosphere via the exhaust pipe.
 4. The method ofclaim 1 wherein the vaporized liquid water is emitted to the atmospherevia a separate pipe.
 5. The method of claim 2 further comprisingfiltering the collected liquid water prior to the pumping.
 6. The methodof claim 1 wherein vaporizing the liquid water using waste heat from theengine comprises: providing the collected liquid water to a vaporizerunit, the vaporizer unit comprising at least one spray nozzle disposedwithin a jacket that is formed at least partially around an exhaustmanifold of the engine; and spraying the collected liquid over theexhaust manifold with the spray nozzles, wherein the sprayed liquidwater is contained within the jacket.
 7. The method of claim 6 furthercomprising pre-heating the collected liquid water with recovered wasteheat from at least a portion of the exhaust pipe.
 8. The method of claim1 wherein emitting the vaporized liquid water to the atmosphere via theexhaust pipe comprises directing the vaporized liquid water to a vaporport that is in fluid communication with the exhaust pipe.
 9. The methodof claim 6 further comprising making the jacket liquid-tight around theexhaust manifold of the engine.
 10. An apparatus to reduce the volume ofliquid water emitted from an exhaust pipe of a hydrogen-fueled engine,comprising: a vaporizer unit comprising a main body portion, a sprayingassembly and a vapor port portion, and wherein: the main body portionsurrounds at least a portion of an exhaust manifold of the engine; themain body portion is defined by an inner surface and an outer surface;the inner surface is defined in part by at least a portion of theexhaust manifold; the vapor port portion is defined by an opening in thevaporizer unit; the spraying assembly comprises at least one spraynozzle supported by the main body portion and configured to spray liquidwater over at least a portion of the exhaust manifold; a sump coupled tothe exhaust pipe wherein the sump is configured to collect liquid waterrecovered from the exhaust pipe; and a pump coupled to the sump and tothe spraying assembly and configured to provide the collected liquidwater to the vaporizer unit.
 11. The apparatus of claim 10 furthercomprising a liquid-vapor separator placed inline in the exhaust pipe ofthe engine, and wherein the sump is configured to collect liquid waterfrom the liquid-vapor separator.
 12. The apparatus of claim 10 furthercomprising a liquid return line that couples the pump to the vaporizerunit.
 13. The apparatus of claim 12 wherein the liquid return line is atleast partially disposed proximate to a portion of the exhaust pipe thatis between the pump and the exhaust manifold.
 14. The apparatus of claim13 wherein the liquid return line is covered with a heat-retaininginsulation.
 15. The apparatus of claim 14 wherein the heat retaininginsulation material is selected from the group consisting of graphitecomposite, fiberglass, mylar, aluminum and ceramic.
 16. The apparatus ofclaim 10 wherein at least a portion of the exhaust pipe is covered witha heat-retaining insulation to increase the transfer of heat to theliquid return line.
 17. The apparatus of claim 12 wherein theliquid-vapor separator comprises a separator housing that defines anenclosed space interior to the separator housing, and wherein theenclosed space includes a medium to cause a separation of liquid waterfrom water vapor.
 18. The apparatus of claim 17 wherein the medium is asurface area enhancing material selected from the group consisting ofplastic beads, glass beads, ceramic beads, metal wool, fiberglass wool,and expanded metal.
 19. The apparatus of claim 10 wherein: the exhaustmanifold comprises a plurality of separate outlet pipes and a headerthat is connected to the plurality of outlet pipes, and wherein theexhaust pipe is connected to the header; the main body portion isfurther defined by a front face, and four side faces, and wherein: thefront face is substantially rectangular and defined by one or moreopenings for the one or more output pipes; the four side faces extendgenerally perpendicularly from an edge of each of the four sides of thefront face to define an open sided box defining an interior space; andwherein the main body portion is positioned on the exhaust manifold suchthat each of the side faces are affixed to the exhaust manifold, and theone or more output pipes traverse the interior space of the main bodyportion and exit the one or more openings on the front face of the mainbody portion.
 20. The apparatus of claim 10 wherein the main bodyportion is composed of a material selected from the group consisting ofplastic, graphite composite, aluminum, steel and ceramic.
 21. Theapparatus of claim 10 further comprising a drain channel disposed in theexhaust pipe between the liquid-vapor separator and an ambient exhaustpoint of the exhaust pipe, and wherein the drain channel is drained intothe sump.
 22. The apparatus of claim 21 further comprising a filterscreen positioned between the exhaust pipe and the drain channel. 23.The apparatus of claim 10 further comprising a fluid deflector disposedwithin the exhaust pipe to prevent water from the sump from re-enteringthe exhaust pipe as exhaust gasses flow through the liquid-vaporseparator.
 24. The apparatus of claim 10 wherein the spraying assemblycomprises two nozzles supported by the main body portion and configuredto spray liquid water over at least a portion of the exhaust manifold.25. The apparatus of claim 10 wherein the inner surface is coated with asealant.
 26. The apparatus of claim 25 wherein the sealant is a hightemperature silicone.
 27. The apparatus of claim 10 wherein the openingin the vaporizer unit is coupled to the exhaust pipe via a vapor pipe.28. The apparatus of claim 10 wherein the opening in the vaporizer unitis vented directly to atmosphere outside of the body portion.
 29. Theapparatus of claim 10 wherein the opening in the vaporizer unit isvented to the liquid-vapor separator via a secondary pipe.
 30. Theapparatus of claim 29 wherein the secondary pipe encases the exhaustpipe.
 31. A system to reduce the volume of liquid water emitted from thetailpipe of a hydrogen fueled engine, comprising: means for collectingliquid water that condenses in the tailpipe from exhaust gasses emittedby the engine; means for vaporizing the liquid water using waste heatfrom the engine; and means for returning the vaporized collected waterto the atmosphere via the tailpipe.
 32. An apparatus comprising: ajacket configured to cover at least a portion of an exhaust manifold ofan engine; a liquid collector configured to collect liquids within anexhaust pipe connected to the exhaust manifold; a pump configured topump liquids from the liquid collector to the jacket; and a sprayassembly configured to spray liquids from the pump over the portion ofthe exhaust manifold covered by the jacket.